SiC, which is superior to Si etc., in terms of heat resistance, mechanical strength, and the like, has been attracting attention as a new semiconductor material. Some single crystal SiC substrate may originally contain, in its surface, crystal defects or the like.
Patent Document 1 discloses a surface planarization method for planarizing (repairing) a surface of a single crystal SiC substrate. The surface planarization method includes forming a carbonized layer and a sacrificial growth layer on a single crystal SiC substrate, and etching the sacrificial growth layer, for surface planarization. This can produce a high-quality seed substrate for epitaxial growth.
When the sacrificial growth layer is formed, a heat treatment under Si vapor pressure is needed. In Patent Document 1, a storing container shown in FIG. 6 is used for being caused Si vapor pressure. As shown in FIG. 6, a storing container 90 for storing a single crystal SiC substrate 94 includes an upper container 91 and a lower container 92 being fittable to each other. Si 93 is adhered to a wall surface that defines an internal space in the upper container 91 and the lower container 92. This configuration allows Si 93 to be evaporated during the heat treatment. Accordingly, Si vapor pressure can be generated in the internal space of the storing container 90.
In general, a seed crystal produced in the above-described manner is subjected to treatments including epitaxial growth, ion implantation, ion activation, and the like.
Patent Document 2 discloses a method for suppressing sublimation of Si and SiC during ion activation, by performing the ion activation after a carbonized layer (graphene cap) is formed on a surface of a single crystal SiC substrate. After that, with this method, the carbonized layer is removed and the surface of the single crystal SiC substrate is etched under Si vapor pressure in order to remove an insufficient ion-implanted portion. Patent Document 2 discloses a method for placing Si pellets in the storing container in order to be caused Si vapor pressure.